Embolic coil delivery system with retractable mechanical release mechanism

ABSTRACT

An embolic implantation system configured to deliver an embolic implant intravascularly to a treatment site includes an elongated delivery tube to which the embolic implant is detachably attached by a flexible loop extending through a retaining ring or opening on the embolic implant and an elongated detachment member or pull wire extending through the delivery tube and flexible loop. The pull wire has a bump near its distal end that inhibits the pull wire from moving further distally when the bump presses distally against the flexible loop and/or retaining ring. The flexible loop and retaining ring thereby serve as a distal obstruction obstructing distal movement of the bump and thereby distal movement of the pull wire into the implant.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. application Ser. No.15/891,041, filed Feb. 7, 2018 which is a Divisional of U.S. applicationSer. No. 14/454,773, filed Aug. 8, 2014 and issued as U.S. Pat. No.9,918,718 on Mar. 20, 2018. Each of the parent applications arerespectively incorporated herein by reference in their entirety.

FIELD OF THE INVENTION

The present invention relates to a medical device for placing an embolicdevice at a predetermined site within a vessel of the human body, andmore particularly, relates to a catheter-based deployment system fordelivering an embolic device.

BACKGROUND

For many years, flexible catheters have been used to place variousdevices within the vessels of the human body. Such devices includedilation balloons, radiopaque fluids, liquid medications, and varioustypes of occlusion devices such as balloons and embolic coils. Examplesof such catheter-based devices are disclosed in U.S. Pat. No. 5,108,407,entitled “Method and Apparatus for Placement of an Embolic Coil” andU.S. Pat. No. 5,122,136, entitled “Endovascular ElectrolyticallyDetachable Guidewire Tip For The Electroformation Of Thrombus InArteries, Veins, Aneurysms, Vascular Malformations And ArteriovenousFistulas.” These patents disclose catheter-based devices for deliveringembolic coils to preselected positions within vessels of the human bodyin order to treat aneurysms, or alternatively, to occlude blood vesselsat a particular location.

Coils which are placed in vessels may take the form of helically woundcoils, or alternatively, may take the form of randomly wound coils,coils wound within coils or other such coil configurations. Examples ofvarious coil configurations are disclosed in U.S. Pat. No. 5,334,210,entitled “Vascular Occlusion Assembly” and U.S. Pat. No. 5,382,259,entitled “Vasoocclusion Coil with Attached Tubular Woven or BraidedFibrous Covering.” Embolic coils are generally formed of a radiopaquemetallic material, such as platinum, gold, tungsten, or alloys of thesemetals. Often, several coils are placed at a given location to occludethe flow of blood through the vessel, or aneurysm, by promoting thrombusformation at the particular site.

In the past, embolic coils have been placed within the distal end of acatheter. When the distal end of the catheter is properly positioned,the coil may then be pushed out of the end of the catheter with a pushermember to release the coil at the desired location. This procedure forplacement of an embolic coil is conducted under fluoroscopicvisualization such that the movement of the coil through the vasculatureof the body may be monitored and the coil placed at the desiredlocation.

Another procedure involves the use of glue or solder for attaching thecoil to a guidewire, which in turn, is placed within a flexible catheterfor positioning the coil within the vessel at a preselected position.Once the coil is in the desired position, the coil is held in positionby the catheter and the guidewire is pulled proximally to thereby causethe coil to become detached from the guidewire and released from thecatheter. Such a coil positioning system is disclosed in U.S. Pat. No.5,263,964 entitled “Coaxial Traction Detachment Apparatus and Method.”

Still another coil positioning procedure is that of having a catheterwith a socket at the distal end of the catheter for retaining a ballwhich is, in turn, bonded to the proximal end of the coil. The ball,which is generally larger in diameter than the outside diameter of thecoil, is placed in the socket within the lumen at the distal end of thecatheter and the catheter is then moved into a vessel in order to placethe coil at a desired position. Once the position is reached, a pusherwire with a piston at the end thereof is pushed distally from theproximal end of the catheter to push the ball out of the socket in orderto release the coil at the desired position. Such a system is disclosedin U.S. Pat. No. 5,350,397, entitled “Axially Detachable Embolic CoilAssembly.”

Another procedure for placing an embolic coil within a vessel is that ofusing a heat releasable adhesive bond for retaining the coil at thedistal end of the catheter. One such system uses laser energytransmitted through a fiber optic cable to apply heat to the adhesivebond in order to release the coil from the end of the catheter. Such aprocedure is disclosed in U.S. Pat. No. 5,108,407 entitled “Method andApparatus for Placement of an Embolic Coil.”

Yet another coil deployment system incorporates a catheter having alumen throughout the length of the catheter and a distal tip forretaining the coil for positioning the coil at a preselected site. Thedistal tip of the catheter is formed of a material which exhibits thecharacteristic that when the lumen of the catheter is pressurized thedistal tip expands radially to release the coil at the preselected site.Such a deployment system is disclosed in U.S. Pat. No. 6,113,622entitled “Embolic Coil Hydraulic Deployment System.”

Still another coil deployment system incorporates an interlockingmechanism on the coil. The interlocking end on the embolic coil coupleswith a similar interlocking mechanism on a pusher assembly. A controlwire which extends through the locking mechanism secures the coil to thepusher assembly. The pusher assembly and embolic coil are initiallydisposed within the lumen of a catheter. When the embolic coil is pushedout of the end of the catheter for placement, the control wire isretracted, and the coil disengages from the pusher assembly. Such adeployment system is disclosed in U.S. Pat. No. 5,925,059, entitled“Detachable Embolic Coil Assembly.”

Yet another coil deployment system incorporates an embolic devicedetachably mounted on the distal portion of a pusher member and held inplace with a connector thread or fiber. The fiber passes through acutter member that may be activated to cut the connector fiber. Once theconnector fiber is cut, the embolic device is released. Such adeployment system is disclosed in Published U.S. Patent Application No.2002/0165569, entitled “Intravascular Device Deployment MechanismIncorporating Mechanical Detachment.”

Still another coil deployment system incorporates an embolic device witha stretch resistant member there through. The distal end of the stretchresistant member attaches to the embolic coil and the proximal end ofthe stretch resistant member is detachably mounted on the pusher memberthrough various means such as adhesive, or by a connector fiber adheredto or tied to the pusher member, and is detachable by the application ofheat. Such a deployment system is disclosed in Published U.S. PatentApplication No. 2004/0034363, entitled “Stretch Resistant TherapeuticDevice.”

A yet further coil deployment system incorporates a pusher wire with astiff wavy-shaped end segment which is coupled to the embolic coil andis placed in the lumen of the catheter. The coil is advanced through thecatheter until it reaches a predetermined site in the vessel at whichtime the pusher wire is retracted and the embolic coil is released. Sucha system is disclosed in U.S. Pat. No. 6,203,547, entitled“Vaso-occlusion Apparatus Having A Manipulable Mechanical DetachmentJoint And A Method For Using The Apparatus.”

A still further embolic device deployment system for placement of anembolic device, or coil, includes a delivery catheter and a flexiblepusher member. The embolic device is retained by an interlockingmechanism which includes a detachment member which extends through anaperture in an engagement member. The engagement member engages a ringon the embolic device. When the detachment member is withdrawn from theaperture, the embolic device is released. One such deployment system isdisclosed in U.S. Pat. No. 7,377,932, entitled “Embolic Coil DeliverySystem with Mechanical Release Mechanism.”

A yet still further embolic device deployment system for placement of astretch-resistant embolic device, or coil, includes a delivery catheterand a flexible pusher member. The embolic device is retained by aninterlocking mechanism with a detachment member which extends through anaperture in an engagement member. The engagement member enables a ringon the embolic device, where a stretch-resistant member extends throughthe coil. When the detachment member is withdrawn from the aperture, thestretch-resistant member enables the embolic device to release withoutdifficulty. One such deployment system is disclosed in U.S. Pat. No.7,371,251 entitled “Stretch Resistant Embolic Coil Delivery System WithMechanical Release Mechanism.”

However, all of the above systems have their drawbacks, including somedifficulty in positively and smoothly releasing the embolic coil. Thus,a system is still needed to accomplish these goals.

SUMMARY

Thus, an example of an embolic device deployment system to place anembolic device at a predetermined site within a vessel can include anelongated flexible deployment catheter having a first lumen extendingtherethrough and having proximal and distal ends. A notch section can bedisposed in the first lumen of the catheter and can form a second lumen.An embolic device can have a retaining ring at the proximal end anddisposed distal of the catheter. An engagement member can be partiallydisposed in the second lumen and include a distal loop extending throughthe retaining ring, and a proximal loop extending into the first lumen.Further, an elongated detachment member can slide within the first lumenof the deployment catheter and be disposed through the proximal anddistal loops. The detachment member can have a detachment member bumpdisposed between the proximal and distal loops. Therefore, when thedetachment member is disposed within the distal loop and the distal loopis disposed within the retaining ring, the embolic device is in anengaged position, retaining the embolic device proximal to the tip ofthe catheter. However, when the detachment member is pulled proximally,the detachment member is withdrawn from the distal loop, and thedetachment member bump contacts the proximal loop. These acts assist inthe disengagement of the distal loop from the retaining ring to therebyrelease the embolic device. The embolic device can be an embolic coil.

The embolic device deployment system can also have a retainer bumpdisposed on a proximal end of the engagement member and located outsidethe second lumen. The retainer bump prevents movement of the engagementmember in the distal direction. In one example, this is accomplishedbecause the retainer bump has at least one dimension larger than thesecond lumen. However, the retainer bump and the detachment member bumpare sized to not interfere with each other.

Another example of an embolic device deployment system functions similarto the above, including having an elongated flexible deployment catheterhaving a first lumen extending therethrough and having proximal anddistal ends. However, this example includes an expandable member havinga contracted state and an expanded state and having at least twoapertures therethrough. The expandable member is disposed in the firstlumen and fixed in the first lumen by the expanded state. An engagementmember can be partially disposed in at least one aperture, and have adistal loop extending through the retaining ring, and a proximal loopextending into the first lumen. An elongated detachment member can beslidably disposed within the first lumen and another of the apertures.Further, it can be disposed through the proximal and distal loops. Thedetachment member can also have a detachment member bump disposed on thedetachment member between the proximal and distal loops. Similar to theabove, when the detachment member is disposed within the distal loop andthe distal loop is disposed within the retaining ring, the embolicdevice is in an engaged position. Then, when the detachment member ispulled proximally, the detachment member is withdrawn from the distalloop, and the detachment member bump contacts the proximal loop toassist in the disengagement of the distal loop from the retaining ringto thereby release the embolic device.

The embolic device deployment system can further include a retainer bumpdisposed on a proximal end of the engagement member proximal to theaperture. The retainer bump can prevent movement of the engagementmember in the distal direction. The retainer bump can also have at leastone dimension larger than the aperture. In another example, the retainerbump and the detachment member bump are sized to prevent interferencewith each other.

A method of deploying an embolic device can includes the steps ofdisposing an engagement member having distal loop located within aretaining ring of the embolic device. The embolic device can be retainedby disposing a distal end of a detachment member in the engagementmember distal loop and disposing the detachment member through anengagement member proximal loop. A detachment member bump can be locatedbetween the engagement member proximal and distal loops. To deploy,proximally withdraw the detachment member from the engagement memberdistal loop and contacting the detachment member bump with theengagement member proximal loop, deploying the embolic device. Themethod can include placing a catheter and the embolic device in a bodylumen and moving the catheter and embolic device to a treatment site.

Other examples dispose a retainer bump on the engagement member andrestricting distal movement of the engagement member with the retainerbump. In more detail, the engagement member and the detachment membercan be disposed in a catheter have a notch formed therein. A portion ofthe engagement member can be located in the notch and then restrictingthe movement includes preventing the retainer bump from passing thoughthe notch and engaging the retainer bump and the notch to restrictdistal movement.

BRIEF DESCRIPTION OF THE DRAWINGS

This invention is described with particularity in the appended claims.The above and further aspects of this invention may be better understoodby referring to the following description in conjunction with theaccompanying drawings, in which like numerals indicate like structuralelements and features in various figures. The drawings are notnecessarily to scale, emphasis instead being placed upon illustratingthe principles of the invention.

The drawing figures depict one or more implementations in accord withthe present teachings, by way of example only, not by way of limitation.In the figures, like reference numerals refer to the same or similarelements.

FIG. 1 is an enlarged, partially sectional view of an example of anembolic coil delivery system in accordance with the present invention;

FIG. 2 is a cross-section along II-II of FIG. 1 ;

FIGS. 3A, 3B, and 3C are enlarged, partially sectional views,illustrating releasing the coil in the coil delivery system of FIG. 1 ;

FIG. 4 is an enlarged, partially sectional view of another example of acoil delivery system; and

FIG. 5 is a flow chart of the method of delivering a coil of the presentinvention.

DETAILED DESCRIPTION

FIG. 1 generally illustrates an example of a vascular occlusive emboliccoil delivery system 100 which can include an elongated deliverycatheter 2 that may generally comprise a small soft tube and may be astructure of flexible plastic having two ends. The catheter 2 may alsocomprise a braid or coil reinforced composite construction having aninner layer, a reinforcement layer, and an outer layer. Theconstructions may include soft polyurethane inner and outer layers thatare fused around braided polymer monofilaments. Spiral or coilreinforcement may be used to improve the catheter 2 hoop strength andkink resistance.

The catheter 2 may have a lumen 4 extending from a proximal end 3 to adistal end 5. The catheter 2 may have a first inner diameter ID thatforms the lumen 4. The catheter 2 can also include an engagement membernotch 6 formed in at least one side of the catheter 2. The engagementmember notch 6 can create a reduced inner diameter ID2 as compared tothe first inner diameter ID. As shown in FIGS. 1 and 2 , an example ofthe catheter 2 may be a hollow tube like structure and a short innertube or notch to act as the engagement member notch 6. At its proximalend 3, the catheter 2 may be attached to a surgical device, and at itsdistal end 5 the catheter may be attached to an embolic device 16 asshown. In one example, the embolic device 16 can eventually release fromthe distal end 5 to be delivered at a desired location.

The catheter size is selected in consideration of the size, shape, anddirectionality of the aneurysm or the body lumens the catheter must passthrough to get to the treatment site. The catheter 2 may have a totalusable length anywhere from 80 centimeters to 165 centimeters and adistal length of anywhere between 5 centimeters to 42 centimeters. Thecatheter 2 may have an inner diameter ID of anywhere between 0.015 and0.025 inches. The outer diameter ID may also range in size and maynarrow at either its proximal end or distal end. The outer diameter maybe 2.7 French or less. While the distal end 5 of the catheter 2 as showncontains the embolic device 16, the catheter tip may be varied in shapeand may curve at an angle.

Also included in the deployment system 100 is an elongated engagementmember 8. The engagement member 8 is disposed within the lumen where itsends are constrained at angles. The engagement member 8, in one example,is formed of a small diameter resilient wire, such as nitinol, andincludes an engagement member proximal loop 10 and distal loop 12. Theengagement member 8 may be a wire device to maintain pushability so itcan be manipulated with respect to the catheter 2. In addition, thedeployment system 100 may include a retainer bump 22 on the engagementmember 8. The retainer bump 22 may vary in shape, size and position inthe catheter 2 so it can restrain the movement of the engagement member8. This restraint, in one example, can be that the retainer bump 22contacts the notch 6 which stops distal motion of the engagement member8.

A detachment member 14 can also disposed through the lumen 4 of thecatheter 2. The detachment member 14, in one example, may be anelongated retractable fiber that may begin at the proximal end 3 of thecatheter 2 and pass through to the distal end 5. The detachment member14 can pass through the engagement member proximal loop 10 and throughthe engagement member distal loop 12. The detachment member 14 can serveto interlock the embolic device 16 at the distal end 5 of the catheter 2until such time as the detachment member 14 is withdrawn proximally. Thedetachment member 14 can be attached to a surgical device at itsproximal end. The detachment member 14 preferably takes the form of asmall diameter elongate filament, however, other forms such as wires ortubular structures are also suitable. While the detachment member 14 ispreferably formed of nitinol, other metals and materials such asstainless steel, PTFE, nylon, ceramic or glass fiber and composites mayalso be suitable.

The detachment member 14 can also include a detachment member bump 24disposed near the distal end of the detachment member 14. As noted inFIG. 1 , the detachment member bump 24 can be located between theproximal and distal engagement member loops 10, 12. The detachmentmember bump 24 can be sized and shaped accordingly so it is larger, andthus cannot pass through, the engagement member loops 10, 12. Note, thatin one example, both the retainer bump 22 and the detachment member bump24 are sized and shaped so as to not interfere with each other.

The deployment system 100 may include an embolic device 16 which, in anexample, takes the form of a helically wound embolic coil disposed atthe distal end 5 of the catheter 2. While the embolic device 16 as isillustrated is shown as a helically wound coil, other types of embolicdevices, such as filaments, braids, foams, expandable meshes and stents,could be delivered using the present deployment system and various othercoil configurations could be delivered using this system. A coil may berelatively stiff and made of stainless steel or it may be soft and madeof platinum. Extremely soft coils may be made with either a spiral shapeor a more complex shape to promote deployment at the desired deliverylocation and to promote a higher packing density. The diameter of a coilis selected in consideration of the size of the aneurismal sac.Generally, the coil device 16 may be very small and thin, ranging in avariety of shapes and sizes. The coil device 16 may come in variousrandom loop designs to conform to the aneurysm shape, and variousdeployments of the coil device may be used. A coil can vary in softnessand in stiffness. The coil size can range from about twice the width ofa human hair to less than one hair's width. The number of loops in acoil may vary. Platinum coils may be between 0.010 inches and 0.025inches in diameter. A coil may vary from 1 to 60 centimeters in length,with some as long as 100 centimeters. A weld, or solder, bead 18 isformed at the distal end of the embolic device 16 to provide anatraumatic tip for the embolic device 16. The proximal end of theembolic device 16 is attached to the edge of a retaining ring 20. In anexample, the retaining ring 20 is coaxial with the proximal end of theembolic device 16.

FIG. 1 illustrates an example of the deployment system 100 when the coil16 is engaged to the system 100. Approximate to the distal end 5 of thecatheter 2, the engagement member 8 is disposed partially within theengagement member notch 6 with the retainer bump 22 proximal of thenotch 6. The engagement member proximal loop 10 is proximal to the notch6 and extends into the lumen 4 of the catheter 2. The engagement memberdistal loop 12 can also be disposed towards the lumen and extendsthrough the retaining ring 20 of the coil device 16 distal of theengagement member notch 6.

The detachment member 14 extends through the lumen 4 and passes throughboth the engagement member proximal and distal loops 10, 12. Thedetachment member bump 24 of the detachment member 14 is disposedbetween the proximal and distal engagement member loops 10, 12. Theinterlocking of the detachment member 14 and the engagement memberdistal loop 12, when the loop 12 is extended through the retaining ring20, holds the coil 16 in place at the tip of the catheter 2.

FIGS. 1 and 3A illustrate an example of a position of the detachmentmember 14 to keep the engagement member 8 engaged with the retainingring 20. The detachment member bump 24 may be shaped and sized to fitinto the inner diameter ID2 of the catheter 2 and it can be positionedbetween the engagement member proximal loop 10 and engagement memberdistal loop 12 without passing through either. FIG. 1 illustrates thesystem in this position before the embolic coil 16 is deployed. FIG. 1shows the position of the detachment member 14 in the lumen 4 of thecatheter 2 where the detachment member bump 24 is near the distal end 5of the lumen 4. The detachment member 14 passes through the engagementmember proximal loop 10 and the distal loop 12 where the engagementmember 8 is constrained. FIG. 1 also illustrates a position of theengagement member 8 with respect to the detachment member 14. FIG. 2 isa cross section of FIG. 1 , illustrating an example that the detachmentmember 14 and engagement member 8 can be positioned where one issuperimposed over the other. The notch 6 separates the detachment member14 and engagement member 8. FIG. 2 illustrates the placement of thenotch 6 creating a second inner diameter ID2 where a portion of thedetachment member 14 is positioned as seen in FIG. 1 .

FIG. 3A shows the direction of the detachment member 14 as it slides outof the engagement member distal loop 12 to release the coil 16. Thedetachment member bump 24 is in a proximal position from where it was inFIG. 1 . FIG. 3A shows an intermediary position of the detachment member14 between its initial engagement in FIG. 1 and its proximal movement tobegin the disengagement of the coil. The arrow illustrates the directionof movement of the detachment member 14.

As shown in FIG. 3B, the detachment member bump 24 begins to slidetoward the proximal end 3 of the catheter 2 until the detachment memberbump 24 contacts or is close to contacting the engagement memberproximal loop 10. At this point, the detachment member 14 has disengagedfrom the engagement member distal loop 12 and there is nothing securingthe distal loop 12 inside the retaining ring 20. In one example, thedistal loop 12 can be manufactured as such to begin removing itself fromthe retaining ring 20. It can be very soft, pliable, in spring tension,or have shape memory proprieties to assist in the loop's 12 removal fromthe ring 20.

The detachment member bump 24 may further assist in disengaging theengagement member 8. FIG. 3C illustrates the detachment member 14 afterfully withdrawing from the engagement member distal loop 12 and thesurgeon continues to move the detachment member 14 proximal of the tipof the catheter 2. The detachment member bump 24 can contact theengagement member proximal loop 10 and, since it cannot pass through theloop 10, proximally displaces the engagement member 8 to assist in thewithdrawal of the engagement member distal loop 12 from the retainingring 20. Once the engagement member 8 fully withdraws from the emboliccoil retaining ring 20 as shown in FIG. 3C, the embolic device 16 isreleased, and the distal end of the engagement member 8 retracts to aposition further internal to the delivery catheter 2.

Both FIGS. 3A and 3B demonstrate the direction of movement of thedetachment member 14. In an additional example, the detachment member 14can be limited when moving in the opposite, distal, direction. Theengagement member (retainer) bump 22 can prohibit the detachment member14 from moving too far forward past the tip of the catheter 2 if anadditional bump (not illustrated) is placed on the detachment member 14proximal to the loop 10.

In an example, a Tuohy-Borst type of clamp is attached on the proximalend of the delivery system 100 and serves to prevent movement of thedetachment member 14 and the engagement member 8 until the surgeonwishes to deploy the coil 16. In a further example, the detachmentmember 14 can be removed completely from the catheter 2, taking theengagement member 8 with it. The catheter 2, in an example, can then beused to deploy other surgical tools, however, the ID may be too small.In another example, the catheter 2 can be used to guide a secondcatheter (not illustrated) over its body after the coil 18 is deployed.In this example, the small ID of the catheter 2 allows it to act as atype of guidewire for a larger catheter.

In FIG. 4 , another example of an embolic coil delivery system 200 isillustrated. The system 200 functions similarly to the system 100described above but can adapt to any generic catheter 202. In theprevious example, the catheter 2 has a notch 6, to retain the engagementmember 8. The system 200 can have an expandable member 230 disposedalong a detachment member 214 and an engagement member 208. Here, theentire system 200 can be disposed within the catheter 202 and theexpandable member 230 is in its minimized configuration. Here, theexpandable member 230 is as small or smaller as the inner diameter ID ofthe catheter 202. Once placed within the lumen 204, the expandablemember 230 can be expanded to contact the catheter 202 and be fixed inplace. Both the engagement member 208 and the detachment member 214 canpass through the expandable member 230 but their respective bumps 222,224 can be constrained as in the example above to prevent over extensionof the engagement member 208 and allow the detachment member 214 toassist in the disengagement of the coil 16. The expandable member 230can be inflatable, expandable, or spring loaded as is known in the art.Further, the expandable member 230 can be a fixed size and adhered tothe catheter 202 using known adhesives.

FIG. 5 illustrates a method of deploying a coil 16 of the presentinvention. An example of a method includes placing a catheter 2 and anembolic device 16 in a body lumen 4 and moving it to a treatment site(step 300). An engagement member distal loop 12 can be disposed within aretaining ring 20 of the embolic coil 16 (step 302). Further, a distalend of a detachment member 14 can be disposed through the engagementmember distal loop 12, locking the embolic device 16 in place (step304). The detachment member 14 can also be disposed through anengagement member proximal loop 10 (step 306). A detachment member bump24 can be disposed between the engagement member proximal and distalloops 10, 12 (step 308). The detachment member 14 can be proximallywithdrawn from the engagement member distal loop 12, disengaging theembolic device 16 (step 310). Further, the detachment member bump 24 cancontact the engagement member proximal loop 10 so as to furtherdisengage the engagement member distal loop 12 from the retaining ring20 (step 312). Additionally, an engagement member enlarged, partiallysectional enlarged, partially sectional (retainer) bump 22 can bedisposed on the engagement member 8 restricting its distal movement(step 314). The engagement member bump 22 can contact a notch 6 in thecatheter 2 to prevent distal movement of the engagement member 8 (step316).

As is apparent, there are numerous modifications of the preferredexample described above which will be readily apparent to one skilled inthe art, such as many variations and modifications of the embolic deviceincluding numerous coil winding configurations, or alternatively othertypes of embolic devices. Also, there are many possible variations inthe materials and configurations of the release mechanism. Thesemodifications would be apparent to those having ordinary skill in theart to which this invention relates and are intended to be within thescope of the claims which follow.

What is claimed is:
 1. An embolic implantation system comprising: anelongated delivery tube configured to traverse vasculature andcomprising a lumen therethrough; an embolic implantable devicecomprising a retaining ring; a flexible loop engaged to the elongateddelivery tube and extending through the retaining ring; an elongateddetachment member being slidably disposed within the lumen of thedelivery tube and the flexible loop so that the embolic implantabledevice is thereby engaged to the delivery tube and the elongateddetachment member is slidable in a proximal direction to exit theflexible loop so that the flexible loop can exit the retaining ring, theelongated detachment member comprising a distal bump extendingtherefrom; a distal obstruction positioned approximate a distal end ofthe delivery tube and shaped to engage the distal bump to obstructdistal movement of the distal bump when the distal obstruction isengaged to the distal bump; wherein the distal obstruction comprises theflexible loop and the retaining ring when the embolic implantable deviceis engaged to the delivery tube; and an engagement member comprising theflexible loop and a proximal loop positioned within the lumen of thedelivery tube approximate the distal end of the delivery tube, whereinthe elongated detachment member further comprises a proximal bump shapedto engage the proximal loop upon proximal movement of the proximal bumpinto the proximal loop.
 2. The embolic implantation system of claim 1,wherein the flexible loop and the proximal loop are affixed within thelumen of the delivery tube.
 3. The embolic implantation system of claim1, wherein the engagement member is slidable, and thereby the flexibleloop and proximal loop are each slidable, in the proximal direction uponproximal movement of the proximal bump when the proximal bump is engagedto the proximal loop.
 4. The embolic implantation system of claim 3,further comprising: an engagement member holder affixed in relation tothe elongated delivery tube through which a portion of the engagementmember is slidably disposed, wherein the engagement member comprises aretainer bump thereon positioned in a proximal direction in relation tothe engagement member holder and sized to engage the engagement memberholder to inhibit distal movement of the engagement member through theengagement member holder.
 5. The embolic implantation system of claim 3,wherein the engagement member is configured to slide in a proximaldirection, upon proximal movement of the proximal bump when the proximalbump is engaged to the proximal loop, to cause the flexible loop to exitthe retaining ring.
 6. An embolic implantation system, comprising: anelongated delivery tube configured to traverse vasculature andcomprising a lumen therethrough; a pull wire slidably disposed in thelumen and comprising a distal bump affixed on a distal portion of thepull wire; an embolic implant comprising an opening; a flexible loopengaged to the elongated delivery tube, extending through the opening ofthe embolic implant, and a looped around the pull wire so that theembolic implant is detachably attached to the elongated delivery tubeand the distal bump on the pull wire is obstructed from sliding distallythrough the flexible loop; and an engagement member comprising theflexible loop and a proximal obstruction positioned within the lumen ofthe delivery tube approximate a distal end of the delivery tube, whereinthe pull wire further comprises a proximal bump shaped to engage theproximal obstruction upon proximal movement of the proximal bump intothe proximal obstruction.
 7. The embolic implantation system of claim 6,wherein the flexible loop and the proximal obstruction are affixedwithin the lumen of the delivery tube.
 8. The embolic implantationsystem of claim 6, wherein the engagement member is slidable, andthereby the flexible loop and proximal obstruction are each slidable, ina proximal direction upon proximal movement of the proximal bump whenthe proximal bump is engaged to the proximal obstruction.
 9. The embolicimplantation system of claim 8, further comprising: an engagement memberlumen affixed in relation to the elongated delivery tube and throughwhich a portion of the engagement member is slidably disposed, whereinthe engagement member comprises a retainer bump thereon positioned in aproximal direction in relation to the engagement member lumen and sizedto inhibit distal movement of the engagement member through theengagement member lumen.
 10. The embolic implantation system of claim 8,wherein the engagement member is configured to slide in a proximaldirection, upon proximal movement of the proximal bump when the proximalbump is engaged to the proximal obstruction, to cause the flexible loopto exit the opening of the embolic implant.
 11. A method comprising:engaging a flexible loop to an elongated delivery tube; extending theflexible loop through a retaining ring of an embolic implant;positioning a distal bump extending from a pull wire and near a distalend of the pull wire; extending a pull wire through a lumen of thedelivery tube and an opening of the flexible loop to thereby engage theembolic implant to the delivery tube; positioning an obstruction in adistal direction in relation to the distal bump which obstructs distalmovement of the pull wire when the distal bump is pushed distallyagainst the obstruction; positioning the pull wire so that it isslidable through the delivery tube in a proximal direction to exit theopening of the flexible loop; positioning the flexible loop and theretaining ring to form the obstruction so that the flexible loop andretaining ring obstructs distal movement of the pull wire when thedistal bump is pushed against the flexible loop and/or the retainingring; and positioning a proximal bump extending from the pull wire andin the proximal direction in relation to the distal bump, andpositioning a proximal aperture within the delivery tube and in thedistal direction in relation to the proximal bump, the proximal aperturebeing sized to inhibit the proximal bump from passing therethrough. 12.The method of claim 11, further comprising: affixing the proximalaperture and flexible loop to the delivery tube.
 13. The method of claim11, further comprising: joining the flexible loop and the proximalaperture to a slidable engagement member so that the flexible loop andproximal aperture are collectively slidable in the proximal directionupon proximal movement of the proximal bump against the proximalaperture.
 14. The method of claim 13, further comprising: affixing aretainer bump on the engagement member; and disposing a portion of theengagement member through a notch sized such that the retainer bump isinhibited from passing therethrough and the retainer bump is positionedin a proximal direction in relation to the notch.
 15. The method ofclaim 13, further comprising: sliding the engagement member in theproximal direction, upon proximal movement of the proximal bump againstthe proximal aperture to cause the flexible loop to exit the retainingring.